四川盆地东南部下志留统龙马溪组一段页岩微—纳米观地质特征

发布时间：2018-05-26 16:47

本文选题：四川盆地 + 页岩　；参考：《天然气工业》2017年09期

【摘要】：下志留统龙马溪组一段是四川盆地东南部页岩气勘探开发的目标层系之一,以往对其地质特征的研究多停留在单方面、定性层面。为此,在钻井岩心观察与描述的基础上,应用微—纳米分析技术和模拟技术,对该层系的微—纳米观地质特征进行了分析。结果显示:(1)页岩矿物组成横向发育稳定,但纵向变化明显,龙一1亚段以灰黑色富有机质硅质页岩为主,有机质含量高,石英含量高且主要为有机成因石英;(2)龙一2亚段以灰黑色—黑色含粉砂质页岩及粉砂质页岩为主,较之于龙一1亚段,其砂质含量明显增多,TOC和石英含量则相对较低;(3)龙一3亚段主要为黑灰色黏土质页岩,硅质矿物含量较低,有机质常富集在黏土矿物间呈断续顺层分布;(4)该区页岩主要发育有机质孔隙、黏土矿物孔隙、脆性矿物孔隙和裂缝(含页理缝)等4种储集空间类型,其中有机质孔隙十分发育,多数为纳米级,是页岩气赋存的主要储集空间;(5)龙一_1亚段属于IUPC分类方案中的中孔,孔隙度和渗透率均较高,连通性中—差,喉道直径变小,向上到龙一_2、龙一_3亚段则以IUPC分类方案的大孔为主,但孔隙度降低、连通性变差;(6)该区页岩孔缝细小,孔隙表面积大,对页岩气具有很强的吸附能力,吸附气量随压力增加而增加,页岩气在低速渗流时呈现滑脱效应,渗透率和孔隙压力越小,滑脱效应越明显。
[Abstract]:The first member of Longmaxi formation of Lower Silurian is one of the target strata for shale gas exploration and development in southeastern Sichuan Basin. Based on the observation and description of drilling cores, the micro- nano geological characteristics of the strata are analyzed by using micro- nano analysis and simulation techniques. The results show that the mineral composition of the Shale is stable in the transverse direction, but the longitudinal change is obvious. In the Long-1 submember, the gray and black organic-rich siliceous shale is dominant, and the content of organic matter is high. The content of quartz is high and it is mainly organic. The Long-2 submember is mainly composed of grey-black silty shale and silty shale, compared with Long-1 submember. The content of TOC and quartz is relatively low. The main submember of Long-3 is black gray clay shale, and the content of siliceous minerals is relatively low. The organic matter is usually enriched in the clay minerals and distributed in intermittent bedding. In this area, the shale mainly develops four types of reservoir space, such as organic matter pores, clay mineral pores, brittle mineral pores and fractures (including polymorphic fractures). The pores of organic matter are well developed, mostly nanoscale, which is the main reservoir space for the occurrence of shale gas. The submember of Long-1 belongs to the mesopore in the IUPC classification scheme. The porosity and permeability are high, the connectivity is medium to poor, and the throat diameter is smaller. Up to Longyi 2, the submember 3 of Longshan is dominated by the large pore of IUPC classification scheme, but the porosity decreases, and the connectivity becomes worse. (6) the shale pore fracture in this area is small, the pore surface area is large, and the shale gas has a strong adsorption capacity. The amount of adsorbed gas increases with the increase of pressure, shale gas shows slippage effect at low speed percolation, and the smaller the permeability and pore pressure, the more obvious the slippage effect.
【作者单位】：中国石化页岩油气勘探开发重点实验室;中国石化石油勘探开发研究院;中国石化无锡石油地质研究所;
【基金】：国家科技重大专项“彭水地区常压页岩气勘探开发示范工程”(编号:2016ZX05061)
【分类号】：P618.13

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